An EL display apparatus including a plurality of EL elements that emit light and are arrayed does not require backlight, and places no limitations on a viewing angle, and therefore is under development as an image display apparatus of the next generation.
In the EL display apparatus, the EL element is a current-driven light-emitting element whose brightness is controlled by an amount of current passed there through. A passive matrix type and an active matrix type are provided as methods for driving the EL elements. Although the passive matrix method has simple pixel circuits, it is difficult to achieve a large-scaled and high-definition display. For this reason, in recent years, an EL display apparatus of an active matrix type provided with a drive transistor for each of the pixel circuits has formed a mainstream.
The drive transistor and a peripheral circuit thereof are formed generally of thin film transistors using poly silicon, amorphous silicon, or the like. The thin-film transistor is suitable for the large-scaled EL display apparatus because it is easy to fit for upsizing and inexpensive, although it has some drawbacks such as poor mobility and large changes in the threshold voltage with time. Further, there have been some studies also conducted for measures to overcome the changes in the threshold voltage with time, which is a drawback of the thin film transistor, by working on the pixel circuits.
When the EL display apparatus of this type is manufactured, the thin film transistor in the pixel may be broken or damaged by electrostatic discharge during the manufacturing process. Therefore, a panel inspection is performed during a manufacturing process as other display apparatuses need it (see Patent Literature 1).